Flotation separation of metallic sulfide ores



United States Patent 3,425,551 FLOTATION SEPARATION OF METALLIC SULFIDE ORES Robert E. Baarson, La Grange, and Paul L. Du Brow,

Chicago, Ill., assignors, by mesne assignments, to

Armour Industrial Chemical Company, a corporation of Delaware No Drawing. Filed Aug. 15, 1966, Ser. No. 572,240 U.S. Cl. 209-166 7 Claims Int. Cl. B03d 1/14 ABSTRACT OF THE DISCLOSURE Dithiocarbonates and di-dithiocarbonates as collectors in froth flotation separation of sulfide minerals from metallic sulfide ores, particularly oxidized metallic sulfide ores.

This invention relates to a process for froth flotation separation of metallic sulfide ores, and more particularly to the use therein of dithiocarbonate compounds as flotation collectors.

In treating crude ores and mineral products to separate the valuable minerals, such as copper, lead and zinc, from the crude material, the process of froth floatation depends for its efficacy on the ability of the collector to wet selectively some constituents of the crude material while other desirable mineral particles of the crude material remain unwetted and adhere to air bubbles which float to the surface of the mixture and are removed as a concentrate in the froth. Coating finely-divided mineral particles is accomplished by agitating a mixture of ore, Water and a suitable chemical collector in a conditioner for a short period of time during which the chemical attaches to or associates with the surface of the mineral particles to form a new surface which is more water repellent than the original surface and which is thereby air avid and tends to more easily adhere to air bubbles injected into the system. Sodium ethyl xanthra-te has been previously used as a collector. Minerals that naturally tend to resist wetting may be treated so that their surfaces will be wetted and they will then sink in the Water and not be floated with the concentrates containing desired mineral particles.

An object of this invention is to provide a process in which dithiocarbonate compounds are employed as flotation collectors in the separation of metallic sulfide ores, and particularly oxidized metallic sulfide ores.

Another object is to provide a process in which dithiocarbonate compounds are used in the recovery of copper sulfide.

A further object is to provide a process in which flotation collectors in the nature of dithiocarbonate compounds and their alkali metal salts derived from quaternary ammonium compounds are useful in the flotation treatment of oxidized copper sufide mineralization.

Other specific objects and advantages will appear as the specification proceeds.

The dithiocarbonates which are useful as collectors in our process have the following structure:

wherein X is a monovalent cation selected from the group consisting of an alkali metal and a quaternary ammonium radical having the structure (R R R R N)+, each R R R and R is selected from the group consisting of ali phatic hydrocarbon radicals having from 1 to 22 carbon atoms, provided that at least one and not more than 2 of the R R and R radicals contain from 6 to 22 carbon atoms; y is an integer from 1 to 2; and M is selected from the group consisting of R and (CI-I R R R NOCSS wherein each R R and R is selected from the group consisting of alkyl radicals having from 1 to 3 carbon atoms and x is an integer from 2 to 4.

The hereinabove described dithiocarbonates maybe derived from quaternary ammonium com-pounds. The dithiocarbonates can also be prepared from quaternized polyalkylene polyamines such as those manufactured by Armour Industrial Chemical Company, a division of Armour and Company, under the trademark Duoquad, or from quaternized imidazolines.

Alkali metal radicals coming within the hereinabove definition of X include sodium, potassium, rubidium and cesium. However we prefer to employ sodium as the alkali metal radical contained in the collectors useful to our process.

Examples of long chain aliphatic hydrocarbon radicals as occurrences of R containing from 6 to 22 carbon atoms Within the hereinabove definition of R include hexyl, heptyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, octadecenyl, octadecadienyl, octadecatrienyl, decosy, eicosyl, and mixtures of the foregoing radicals such as are contained in naturally occurring glycerides such as coconut oil, tallow, soybean oil, and the like. These long chain aliphatic hydrocarbon radicals may be either straight or branched chain, saturated or unsaturated.

Examples of short chain aliphatic hydrocarbon radicals as occurrences of R containing from 1 to 6 carbon atoms within the hereinabove definition of R include methyl, ethyl, propyl, :butyl and pentyl. We prefer to employ methyl.

Especially useful collectors which can be utilized in the practice of our process are dithiocarbonates derived from quaternary ammonium compounds with the trademark Arquad, by Armour Industrial Chemical Company, a division of Armour and Company, having the letter designation C for the symbol coco indicating that the long chain hydrocarbon radicals in the compound are mixtures derived from coconut oil, the letter S for the symbol soya indicating mixtures derived from soybean oil, and the letter T for the symbol tallow indicating mixtures derived from tallow.

In deriving the desired dithiocarbonates, the quaternary ammonium hydroxide is reacted with carbon disulfide in the presence of sodium hydroxide to form the sodium salt of dithiocarbonate, for example, N,N,N-trimethyl-N-cocoammonium sodium dithiocarbonate. The dithiocarbonates having a quaternary ammonium cation may be formed by omitting the sodium hydroxide, viz. Di (N,N,N-trimethyl N cocoammonium) dithiocarbonate. In preparing the dithiocarbonates from quaternized polyalkylene polyamines, the di-dithiocarbonate is formed, viz. N,N dimethyl-N-coco-N',N',N' trimethyl trimethylene di-ammonium di-(sodium dithiocarbonate).

In the practice of the process of this invention, suitable mineral containing sulfide ores may be comminutated to a suitable size for flotation by any of the methods known such as crushing and then grinding in a ball mill. Lime may 'be added to obtain a pH in the alkaline range. We prefer in the laboratory to grind a 500 gram sample of ore for 2 minutes in a laboratory ball mill at about 50% solids in a Water suspension and add CaO to obtain a pH of 12.0 to 12.3. The ground ore, water and lime mixture (called a pulp) may be charged directly to a flotation collector such as a Fagergren cell for flotation and the pulp may be further diluted with water. A frother, such as pine oil, and the collector may then be added to the cell and the water suspension of finelydivided metallic sulfide ores is conditioned before the forced introduction of air into the system. We prefer to add frother at about 0.04 #/t. (pounds of chemical per ton of dry ore), collector at a rate of from about 0.005 to 0.5 #/t. and an additional increment of about 0.04 #/t. frother after 4 minutes of float time. In synthesizing the collector we prefer to prepare it at various concentrations in isopropyl alcohol or other suitable alcohols as solvents in order to facilitate collector addition to the cell, although the collector may be added in solid form or in a water solution. Flotation may be conducted for from about 3 minutes to about 15 minutes or longer with varying concentrates being collected. We prefer a conditioning time of one minute and flotation for 7 minutes, with only one rougher concentrate containing floated desirable mineral particles being collected.

The above-described process utilizing dithiocarbonate compounds provides exceptional flotation selectivity for copper sulfide mineralization, especially of oxidized copper sulfide ores.

The following Specific examples are given to illustrate and to more fully and clearly disclose the present process, but are not to be construed as limiting the scope of our invention:

EXAMPLE I In each test a 500 gram sample of fresh copper sulfide ore analyzing 4.0 to 4.5% Cu was ground in a laboratory ball mill to the approximate size distribution shown in Table I at 50% solids in a water suspension. Lime was added to obtain pH 12.0. The ground ore pulp was transferred to a Fagergren laboratory flotation cell where the ore pulp was conditioned for 1 minute after the addition of the collector and the frother as indicated in Table II. Following conditioning, flotation was conducted for minutes, then an additional increment of 0.04 #/t. of frother was added to the cell, and flotation continued for a total of 9 minutes. Table II shows the collector and frother applied and the reagent addition rates used. Table III shows the metallurgical results obtained.

TABLE I.SC BEEN ANALYSIS-BALL MILL GRIND Mesh size fraction Weight percent Accumulative weightpercent TABLE II 'Iest Col- Iso Pine No. Collector lector, propanol, oil, #/T #IT #IT 1 Di-(N,N-dimcthyl-N,N- 0. 133 0.200 0. 0S

dicoco ammonium) dithiocarbonatc. 2 N,N-dirncthyl-N,N- 0. 074 0. 222 0.08

dicoco ammonium sodium dithiocarbonate.

3 Di-(N,N,N-trimethyl-N- 0. 079 0. 237 0.08

cocoammonium) dithiocarbonate. 4 Std. 0.06 0.08

1 Miner-ac 27, a Xanthogen sulfate.

TABLE III Analyses, weight percent Cu Distribution, Test No. weight percent Concentrate Tails recovery of Cu in concentrate 1 2G. 20 0. I8 96. 40 2 24. 04 0. I8 96. 64 3 29. 87 0. 37 02. 42 4 16. 11 0. 15 97. 40

EXAMPLE II The test procedure with respect to grinding was the same as in Example I. The ore used was the same as that in Example I except that it had been subject to atmospheric oxidation in storage for up to 2 years. The ore pulp was conditioned in the flotation cell for about 1 minute with the collector and frother as indicated in Table IV. After 4 minutes of flotation, an additional l increment of 0.04 t. frother was added to the cell and flotation continued for a total of 9 minutes. No. artificial sulfldization was used in the referenced tests. Table V shows the metallurgical results obtained.

TABLE IV Test Iso- Pine No. Collector #/'I propanol, oil.

1 Di-(N,N,N-trimcthyl-N- 0.051 0.116 0.04

tallowamrnonium) dithiocarbonate. 2 N ,N,N-trimethyl-N- 0.049 0.096 0.04

tallowarnmonium sodium dithiocarbonate. 3 Di(N,N-dirnethyl-N,N- 0.052 0.097 0.04

ditallowammonium) dithiocarbonate. 4 N,N-dimethyl-N,N-(li- 0. 056 0. 088 0. 04

tallow ammonium sodium ditliiocarbonate. 5 Di-(N,N-din1ethy1N,N- 0.049 0.074 0.04

dicocoammonium) ditliiocarbonate. 6 N,N-(limctliyl-N,N-dicoco- 0. 052 0. 156 0. 04

ammonum sodium dithiocarbonatc. 7 Di-(N,N,N-trimcthyl-N- 0.052 0. I56 0. 04

cocoammonium) dithiocarbonate. 8 N,N,N-trimethyl-N-coco- 0. 040 0. 147 O. 04

ammonium sodium dithiocarbonate. 9 N,N-dimethyl-N-eoco- 0.05 0.200 0.04

N,N,N-trimethyl trimethylene (ii-ammonium di-(sodium dithiocarbonate) TABLE V Distribution, Analyses, weight percent Cu weight percent Test No recovery of Cu Concentrate Tails in concentrate EXAMPLE III In each test a 500 gram sample of fresh unoxidized copper ore was ground for 2 minutes in a laboratory ball mill at 50% solids in a water suspension with 13 grams of CaO being added. The ground ore pulp was charged directly to a Fagergren cell for flotation, the pump was diluted to approximately 25% solids, pine oil as frother and the collector were added at the rates indicated in Table VI, and a one minute conditioning time was allowed before the air was turned on. An additional increment of 0.04 t. of pine oil was added after 4 minutes float time and flotation continued for a total of 9 minutes. The pH was maintained at 12.0 to 12.3 with CaO. The collectors used were made up at various concentrations in isopropyl alcohol except in those tests where alcohol addition in Table VI is not noted, in which cases water solutions of the collector were used. Only the first rougher concentrate was collected. The results are shown in Table VII.

5 6 TABLE VII wherein X is a monovalent cation selected from the group Anaylses weight percent Cu Distribution consisting of an alkali metal and a quaternary ammonium Test N Weight percent radical havlng the structure (R R R R N)+, each R R ous a s e o of C11 in R and R is selected from the group consisting of aliphatcmcemmte ic hydrocarbon radicals having from 1 to 22 carbon 32-32 8- 1; 32-22 5 atoms, provided that at least one and not more than 2 29:87 92:42 of the R R and R radicals contain from 6 to 22 carbon Eli-g 8- g-gg atoms; y is an integer from 1 to 2; and M is selected from 5 93:28 the group consisting of R and --(CH R R R NOCSS 10 wherein each R R and R is selected from the group consisting of alkyl radicals having from 1 to 3 atoms and EXAMPLE W x is an integer from 2 to 4.

2. The process of claim 1 in which the ores are copper sulfide ores. 3. The process of claim 2 in which the copper sulfide ores are oxidized.

4. The process of claim 1 in which at least one of the R R and R radicals contains at least 12 carbon atoms and X is sodium. 5. In a process for froth flotation separation of sulfide minerals from metallic sulfide ores, the step of conditioning a water suspension of finely-divided metallic sulfide ores with a dithiocar'bonate, said dithiocarbonate being N,N,N-trimethyl-N-cocoammonium sodium dithio- This series of tests was carried on using the flotation procedure as described in Example III, the ore sample used being considered as severely oxidized due to an extended period of storage. The collector was added to the pulp in the amounts indicated in Table VIII, along with 0.04 t. pine oil. After 4 minutes of flotation, a second increment of 0.01 #/t. pine oil was added and flotation was continued for 5 minutes for a total of 9 minutes flotation time. The collectors were applied either as /2% or 1% water solutions, or as the undiluted chemical as synthesized. The latter existed at various strengths in isopropanol from synthesis procedures. The referenced carbonate tests were run without artificial sulfidation of the oxidized 6. The process of claim 5 in which said dithiocarbonate copper sulfide minerals with inorganic sulfur chemicals. is di-(N,N,N-trimethyl-N-cocoammonium) dithiocarbon- Results were as set out in Table VIII. ate.

TABLE VIII Form of collector #/T isopro- Weight percent Cu Distribution, Test N0. Collector class percent active in Collector, panol added weight percent isopropanol or H2O #IT with collector Rougher Tails recovery of Cu in concentrate 1 N,N,N-trimethyl N-tallowammonium sodium 33.5% in isoprop. 0.0485 0. 096 21.27 0.23 95. 92

dithiooarbonate. 2 ..do in H2O 0.05 0. 099 21. 29 1.10 74. 26 3 Di-(N,N,N-trimethyl-Ntallowammonium) di- 30% in isoprop 0.051 0. 116 27.85 0.37 92. 64

thiocarbonate. 4 do 1% in H20 0. 05 0.116 22.44 0.31 93.28 5 N,N-dimethyl-N,N-ditallowammonium socli- 39% in isoprop 0.056 0.088 24. 49 0.67 87. 50

um dithiocarbonate. 6 Di-(N,N-dimethyl-N,N-ditallowammonium) in isoprop 0. 052 0. 097 22.01 0. 95 80. 34

dithiocarbonate. Di-(N,N-dimethyl-N,N-dicocoammonium) diin isoprop 0.049 0.074 22.19 0.98 77. 51

thiocarbonate. 8 N,N-dimethyl-N,N-dicocoammonium sodium 25% in isoprop 0.052 0.156 23.93 0.30 93.84

dithiocarbonate. 9 Di-(N,N,N-trimethyl-N-cocoammonium) di- 25% in isoprop 0. 052 0. 156 26. 59 0. 88.00

thiocarbonate. 10 N ,N,N-trimethylN-cocoarnmonium sodium di- 25% in isoprop 0. 049 0.147 22. 42 0.33 93. 02

thiocarbonate. 11 Di-dithiocarbonate from Duomeen C 1% in H20 0.05 0.200 21.25 0.22 95. 60 12 Std. Minerac 27 active 0. 054 7. 42 2.08 29. 30

While in the foregoing specification, we have set forth 7. The process of claim 5 in which said dit hiocarbonate specific process steps and collector compounds in consrd- 50 is N,N-dimethyl-N-coco-N,N,N'-trimethyl trimethylene erable detail for the purpose of illustrating embodiments di-amrnonium di-(sodiurn dithi-ocarbonate). of the invention, those skilled in the art will appreclate that variations can be made Without departing from the References Cited spirit and scope of the invention. UNITED STATES PATENTS We claim:

0 1, In a process for froth flotation separation of sulfide 1902317 3/1933 Wnght 209 166 minerals from metallic sulfide ores, the step of condi- FOREIGN PATENTS tioning a water suspension of finely-divided metallic sul- 126 816 5/1959 U S S R fide ores with a dit-hiocarbonate having the following Structure: 60 FRANK W. LUTTER, Primary Examiner.

(MR R R NOCSS) "(X R. HALPER, Assistant Examiner. 

